The speaker describes Leo as highly self-critical: despite users loving Lean, Leo sees its flaws, calls it terrible, and persistently tries to fix them.

“Oh, yeah. So Leo is, like, extremely self-critical. I mean, just there, there are many moments in the story of the development of Lean where he has some users and they love it, and he says it's shit.”

“I mean, he just thinks it's terrible. He-- all he sees is its flaws. He wants to very doggedly fix those flaws.”